Questions[domain-name-system](server)

I've noticed that the "preferred" method of setting the system hostname is fundamentally different between Red Hat/CentOS and Debian/Ubuntu systems.

CentOS documentation and the RHEL deployment guide say the hostname should be the FQDN:

HOSTNAME=<value>, where <value> should be the Fully Qualified Domain Name (FQDN), such as hostname.example.com, but can be whatever hostname is necessary.

The RHEL install guide is slightly more ambiguous:

Setup prompts you to supply a host name for this computer, either as a fully-qualified domain name (FQDN) in the format hostname.domainname or as a short host name in the format hostname.

The Debian reference says the hostname should not use the FQDN:

3.5.5. The hostname

The kernel maintains the system hostname. The init script in runlevel S which is symlinked to "/etc/init.d/hostname.sh" sets the system hostname at boot time (using the hostname command) to the name stored in "/etc/hostname". This file should contain only the system hostname, not a fully qualified domain name.

I haven't seen any specific recommendations from IBM about which to use, but some software seems to have a preference.

My questions:

• In a heterogeneous environment, is it better to use the vendor recommendation, or choose one and be consistent across all hosts?
• What software have you encountered which is sensitive to whether the hostname is set to the FQDN or short name?

This is a Canonical Question about DNS glue records.

What exactly (but briefly) is a DNS glue record? Why are they needed and how do they work?

I am looking to setup a TXT spf record that has 2 included domains... individually:

v=spf1 include:_spf.google.com ~all

and

v=spf1 include:otherdomain.com ~all

What is the proper way of combining them into a single item?

My company runs an internal DNS for mycompany.example

There is a machine on the network that I need to find, but I’ve forgotten its name. If I could see a list, it would probably jog my memory.

How can I list all of the domain records for mycompany.example?

Is there a built-in command line tool that will do reverse DNS look-ups in Windows? I.e., something like <toolname> w.x.y.z => mycomputername

I've tried:

• nslookup: seems to be forward look-up only.
• host: doesn't exist
• dig: also doesn't exist.

I found "What's the reverse DNS command line utility?" via a search, but this is specifically looking for a *nix utility, not a Windows one.